The objectives of this program-project are two-fold, both aspects being relevant to breast cancer. The first of these is an intensive study of biochemical factors underlying certain possible etiologic factors of this disease. Particularly, we will investigate cellular and systemic factors relevant to the "Bulbrook Theory" and the "Estriol Theory" and compare these with a new concept intent on reconciling these "apparently" divergent theories. At the same time, aided by the availability of the appropriate patient material, prognostic aspects relative to proposed treatment modalities will be examined. Thus we plan to compare therapeutic predictions obtained with the "Discriminant Factor" and with the "Estrogen Receptor Assay", as a means of differentiating hormone dependent from independent tumors.